Coupling insert



FIG. 1 is a first top perspective view of the coupling insert.

FIG. 2 is a second top perspective view thereof.

FIG. 3 is a top view thereof.

FIG. 4 is a side view thereof.

FIG. 5 is an end view thereof; and,

FIG. 6 is an opposite end view thereof.

The bottom and other side are identical to the top and side shown in FIGS. 3 and 4, respectively. The broken line showing aspects of the coupling insert is for the purpose of illustrating environmental structure and forms no part of the claimed design. 

The ornamental design for the coupling insert, as shown and described. 